The big problem is water in the cyls. My prehistoric lump has a mercury switch (and I do mean the type of switch, not the OEM's name!) which is designed to cut it if you try & trim up too far. Net result of this is that if it rolls, the engine will die by the time it gets horizontal, so in theory should have stopped turning by the time it goes totally over.

I believe there was a submersion kit that basically put a dump valve on each cylinder & a flood valve on the carbs. Idea being once upright again you opened the valves & cranked for a few seconds to pump the water out / flooded fresh fuel in , then shut the valves & cranked. From memory it was built / sold by Barrus?